Evidence Equivocal but I AM Sticking With EVAR for rAAAs
Medscape Published: February 17, 2015
In this video, I review three trials comparing emergency endovascular aneurysm repair with open surgery for ruptured aneurysms, and find no definitive answers but I deep-dive into the IMPROVE trial. View video here. You must be a registered user of Medscape to view the video. Medscape registration is free! Or if you prefer, read article below.
I'm Frank Veith, professor of vascular surgery at New York University Medical Center and the Cleveland Clinic.
Today I'm going to talk to you about emergency endovascular aneurysm repair (EVAR) of ruptured abdominal aortic aneurysms (rAAAs), and the IMPROVE trial, which dealt with ruptured aneurysms.
Since we first described the use of EVAR for the treatment of ruptured aneurysms in 1994, this form of treatment has gained in popularity across the world but not without controversy. Many groups, like our own, have been able to achieve very good results with EVAR compared with the traditional open repair in the rAAA setting,[2,3] but many groups have found that their results with EVAR were no better than their results with open repair.[4,5]
We speculated that perhaps the groups that had not been able to demonstrate a benefit of EVAR weren't using all of the adjunct strategies that we and others have described to optimize the outcomes with EVAR.[3,6]
However, on the other side of the coin, the groups that didn't get such good results with EVAR said that the groups that did were selecting their patients—lower-risk patients—so that their results were better. As a result of these claims and counterclaims, it is fair to say that EVAR for the treatment of rAAA remains controversial.
And this controversy is in part due to the fact that there is no good level 1 evidence or randomized trials comparing outcomes with EVAR to outcomes with open repair for rAAA. So the controversy continues.
Three long, ongoing, randomized trials have appeared addressing the question: Which is better—EVAR or open repair? One trial was the French ECAR trial, the second trial was the Dutch AJAX trial conducted largely in Amsterdam, and then there was the larger and more important IMPROVE trial, which was conducted in the United Kingdom.
The results of the ECAR and AJAX trials (the French and the Dutch studies) demonstrated equality in the results with EVAR and open repair, but there were serious flaws in both of these trials. Both were small trials and randomized only about 100 patients in each. Most important, neither of these trials randomized high-risk patients with ruptured aneurysms, particularly those in shock or with low blood pressure, and that flaw is extremely important because it is precisely these high-risk patients who are most likely to benefit from EVAR as compared to open repair.
I neglected to mention that neither the ECAR nor AJAX trial used some of the adjunct strategies and technical tricks [eg, fluid restriction and supraceliac aortic balloon control] to optimize the outcome with EVAR.
And finally, the AJAX trial randomized only about 20% of the patients that could have been randomized, so these flaws basically negate the negative outcome [for EVAR] that the ECAR and AJAX trials showed in their results.
The IMPROVE trial is a better trial. It was conducted in 29 high-volume UK centers, and 613 patients were randomized to two groups. One group was called the EVAR strategy group, and the second group was the open-repair group. The early results of this trial were published in the British Medical Journal.
Of interest, this article was widely quoted on the Internet, and in Vascular News it was described in a headline. I quote: "No Difference Between Endovascular and Open Repair." This was a front-page headline about the IMPROVE trial.
Actually, one has to look carefully at these results. There were 316 patients randomized to the EVAR strategy group and 297 patients randomized to the open-repair group. If you look at the 30-day mortality in these two groups, the mortality in the EVAR strategy group was 35% and in the open-repair group it was 37%— no difference. However, one must look carefully at the details in order to assess the results of the IMPROVE trial and its conclusion.
Now, the detailed results in the IMPROVE trial. I have to give you the numbers, although it may be a little confusing. There were 275 patients with rAAAs who were randomized to the EVAR strategy group; of these 275 patients, 154 had an EVAR and their mortality was 27%. In the EVAR strategy group 129 patients—almost half—didn't get an EVAR; they had an open repair or got no treatment, and their mortality was 46%.
In the 261 patients with real, ruptured aneurysms who were [among 275 patients] randomized to open repair, surprisingly, 36 had an EVAR, and their mortality was 22%; [239 patients had either an open repair (220) or no treatment (19), and their mortality was 42%].
If we summarize the results from this IMPROVE trial, the 30-day mortality for all EVAR patients was 26%, whereas the 30-day mortality for all open-repair patients was 37%. When you combine the open repairs with those that didn't get any treatment, the mortality was 43%. Clearly, the EVAR results are better than those of open repair: 26% vs either 37% or 43%—whichever way you want to calculate it.
Moreover, in the IMPROVE trial there were some other relatively minor flaws, and they did not have optimal use of some of the EVAR adjunct strategies that many of us have advocated to get the best results with EVAR. These include fluid restriction, supraceliac aortic balloon control, and diagnosis and treatment of abdominal compartment syndrome. None of these adjuncts or techniques were widely applied in the IMPROVE trial. All three of these have been shown to improve results with EVAR in the rAAA setting.
My conclusion of the three randomized trials, which are level 1 evidence, is that randomized trials in the rAAA setting are difficult to conduct in a meaningful way. There are several flaws in all three of the trials which, in my opinion, render them inconclusive in the EVAR vs open repair controversy. I still believe that EVAR is the best treatment for a ruptured aneurysm, if an EVAR procedure can be done.
That is my opinion. I am Frank Veith.